Jo Hamilton doesn't always refer to her unusual musical instrument by its official, patented name. Only recently put on general sale, it is properly known as an AirPiano – and better that way, no doubt, because it's hard to imagine the music-tech community getting as excited as they have about this piece of kit (which Hamilton will demonstrate at a TED conference in Edinburgh this month) if it were officially known as "the magic plank".

It's a machine that takes some explaining, so Hamilton – who in 2009 became one of the first people in the world to get her hands on a prototype – has stuck to first impressions. "I'm not a particularly tech-minded girl," says the Scottish folk musician, 38. "I've always thought of it as a grid of buttons that hover, invisibly, above this… plank. When you put your hands into one of the virtual spaces, a sound is triggered." At her first live gig with the new instrument, in April last year, someone in the crowd asked how it worked. "Magic," said Hamilton.

Not quite – but unlike virtually every other instrument there's no plucking, strumming, scraping, pressing, striking or clicking required. Instead upward-facing sensors pick up the distance of a player's hands from the base unit, sending the info to a computer and producing pre-programmed sounds. "Playing it is almost dance-like. You have to think about the choreography of a piece."

It makes an AirPiano performance reminiscent of those memorable scenes in Steven Spielberg's Minority Report when Tom Cruise controlled a futuristic computer with his hands. (Hamilton's producer, Jon Cotton, says it makes him think of the "invisible technology" we've seen used for years in sci-fi shows such as Star Trek.) But undercutting the geekery is a definite boho vibe. Those who play the AirPiano must have good spatial awareness, refined limb control – and a willingness to look something like a cross between a really slow hand jiver and one of those absorbed, barefoot types who practise tai chi in the park.

"What appealed to me first was the simplicity of it," says Hamilton. "The fact that you were literally plucking sounds out of the air."

It's such an odd-looking instrument to play, says Cotton, that "people have been sceptical whether she's actually doing anything. There are comments under her YouTube videos: 'She's just playing bits over a backing track!'" But complex-sounding pieces can be created live and entirely on the AirPiano, Hamilton insists. Holding a hand in one of the "virtual button" spaces creates a continuous note, halted when the hand is taken away; by raising and lowering a hand over fringe sensors the player can adjust volume or add special filters to sounds. "Sure, it's got its limitations. But you work around them, and learn to enjoy them."

Hamilton lives and works in Moseley, near Birmingham, but grew up in a remote house in the Scottish Highlands. Musical and isolated, she had learned to play multiple instruments by her early teens, including the viola. "I was shunted on to it because I was tall – you need long arms for the viola – and because nobody else in the school orchestra played it." It has remained her inclination, ever since, to stick up for lesser-loved and quirkier instruments ("The poor viola!"). When she saw an early prototype of the AirPiano being demonstrated on YouTube by its Berlin-based inventor, Omer Yosha, in 2009, she identified a new instrument to champion. She flew out to Germany.

That was in 2009, the year she released a debut album of dreamy, Björk-ish folk, called Gown. Yosher liked Hamilton's music, and agreed to let her take an AirPiano back to the West Midlands. "I was lucky. He'd been approached by several other musicians, begging him for one." Her feedback helped Yosha prepare a shelf-ready AirPiano that is now on sale online for around £900 (www.airpiano.de).

"The best way to learn a new instrument," says Hamilton, "is to write on it." She spent four months fiddling, eventually producing the world's first AirPiano-specific composition, a spare, dreamy ballad called "Alive, Alive". It's this track – all synth hums and plinky electronic noises under Hamilton's low vocal – that she'll play at TED, a biannual conference dedicated to ideas and innovation that has previously hosted performances by the likes of Imogen Heap and David Byrne.

Hopefully it'll go smoothly. New technology, as it will, has revealed the odd hiccup along the way. Low ceilings have occasionally interfered with the instrument's sensors. And not long ago, Hamilton says, she was filming a music video in a warehouse being pumped full of atmospheric smoke when her AirPiano went rogue. "It reacted to the dry-ice particles in the air," and the plank, she says, started playing itself. It wouldn't happen to a viola player.